A spring capture assembly is provided for securing a compression spring of a spring-biased mechanism, such as a spring-biased pressure relief valve, to permit disassembly of the mechanism without risk of damage or injury associate with rapid resiling of the spring from a compressed state. The assembly includes a tool, a housing having an opening for admitting passage of the tool and capturing the spring at one end, a spring retainer, and a compression spring mounted within the housing and captured at one end by said housing and toward an opposite end by the spring retainer. The tool is adapted for mating with the spring retainer and the housing to compress the spring therebetween. The spring capture assembly may be incorporated into a pressure relief valve for venting pressure and/or vacuum from a pressure vessel. Provided also is a method for disassembling a spring-biased mechanism including a spring capture assembly.